1. Field of the Invention
This invention relates in general to wellhead assemblies, and in particular to an apparatus for locking a tubing hanger within a wellhead housing.
2. Description of the Prior Art
In oil and gas wells where the wellhead is located at the surface, a tubing hanger will land within a wellhead housing. The tubing hanger is located at the upper end of one or more strings of tubing through which production fluids will pass. The tubing hanger is sealed and locked to the wellhead housing.
The most typical type of lockdown utilizes threaded rods which extend radially inward in the wellhead housing. Each threaded rod or stud extends through a threaded hole in the wellhead housing. The inner end of each rod is conical for engaging a conical shoulder on the tubing hanger. There are several threaded rods used in each installation. The operator installs the threaded rods by using a wrench to rotate them.
While workable, the threaded rods require that holes be drilled and threaded through the wellhead housing. The rods add to the expense of the lockdown considerably.